The study (which, amazingly, is the first of its kind) measured how the brains of people who struggle with sexually compulsive behavior respond to sexual images. If sex can be addictive in the clinical sense, scientists theorized, then the neural response of sex addicts to pornography should mimic the neural responses of drug or alcohol addicts to their drugs of choice. Instead, researchers found that hypersexual brains don’t react in the same way as other addicts’ brains—in fact, the neural responses to pornography only varied based on levels of sexual libido, rather than on measures of sexual compulsivity. People with higher libidos had more active brain reactions to the sexual images than people with lower libidos, but that was the only correlation. Degrees of sexual compulsivity did not predict brain response at all. If the results of this first study can be replicated, it would represent a major challenge to the notion that sex and pornography can be literally addictive.